This invention relates to delayed turning off of automobile lights. The new automatic headlight switch circuit described herein adds a parking light provision, which U.S. Pat. No. 4,301,390 did not have. There are other changes as well. One basic concept is the same. The lights come on only when the operator physically moves the light switch from the off to the on position. That is, if the switch has been left in the "on" position at night and the next morning the operator turns on the ignition, the lights will not come on unless the operator recognizes the need for lights in which case he reaches for the light switch. Finding it already on, the operator realizes that somebody forgot it. Turning it off and then on again rekindles the lights. Had the switch not been left on, it would always turn on the lights when moved on in the normal manner. That was done before in U.S. Pat. No. 4,301,390 but in a different way.
In the prior patent, the series interuption from the added relay went in the power source line to the headlight switch before it split into the headlight and parking light circuits. Most cars today have separate fusing after the switch. The prior patent did not have separate provision to handle the parking lights. In addition, there was always some residual current flowing in the older circuit to keep it alive at all times.
The parking light problem has not been adequately treated, as far as is known, by any other device. A person may want more than a minute of parking light. Shutting parking lights off after a minute would be undesirable in some situations if an ignition key were not available.
A common approach to prevent forgetting headlights, while still keeping the normal function of the headlights without a key, is to provide a buzzer or other audible device to alert the operator that the key is out and the lights are on. However, buzzers or chimes are often a greater nuisance than anything. Some people build up a mental block to the noise of the alerts. Talking cars avoid simple noisemakers, but some voices are obnoxious as well, and any voice can sometimes be obnoxious. A busy driver would rather just not worry about forgetting lights.